This invention relates to a dental post system for retaining a dental restoration onto a prepared tooth stub, and more particularly to a contoured dental post which more suitably accommodates the actual shape of the tooth canal in the tooth stub.
In the restoration of devitalized dentition, it is a well known practice to utilize a dental post for retaining a superstructure onto the tooth stub. Typically, the tooth stub is prepared by cutting down the damaged tooth to provide a suitable surface, and then drilling into the apical canal a desired depth to provide an enlarged bore for receiving the dental post. The dental post is then inserted and cemented in the bore. An appropriate core is provided or built up on an upper portion of the dental post, and dental restorative material is used to build a superstructure on the core.
Typically, dental posts heretofore utilized have a generally circular cross section. In preparing the tooth stub to receive such dental posts, circular drill bits are utilized to pre-drill the canal to form a circular bore. The dental posts are then inserted into these bores. However, the actual canal in the tooth stub does not have a circular shape, especially at the upper part thereof, where the canal tends to flare outwardly and often approaches an oval shape.
While it would be possible to drill the canal large enough to encompass the flared upper portion to change the oval shape into a circular shape, this would tend to destroy healthy dentition and weaken the existing tooth stub. As a result, prior art practice has been to drill out the canal using only a size of drill bit adequate enough to receive the dental post. Cement was then inserted into the portions of the canal that were larger than the drilled bore so that the cement filled in the gaps between the inserted dental post and the existing canal shape.
The use of such cement to fill in the disparity between the post and the actual canal shape caused problems after the restoration was built up. The cement has a tendency to loosen, permitting the dental restoration to move with respect to the tooth stub. Such movement permits entry of contaminants and decay between the dental restoration and the tooth stub, and may even cause the dental post to be dislodged from the canal, thus requiring replacement of the restoration.